1. Field of the Invention
The present invention relates to a vehicle equipment control device equipped with a plurality of switches for giving commands for various control operations and, in particular, to a vehicle equipment control device capable of automatically discriminating between different kinds of switches.
2. Description of the Related Art
On the instrument panel of an automobile, a number of switches are arranged around the meters. A switch for giving a command for a particular function is not always mounted at the same position. According to the grade, type, etc. of the vehicle, positions where switches for particular functions are mounted may differ. Suppose, for example, a plurality of mounting sections are provided in a horizontal row in the unit attachment portion. In a vehicle of a certain grade, a switch for the driver's seat heater may be mounted to the mounting section at the left-most end, and in a vehicle of another grade, another switch for another function, for example, traction control, may be mounted to the same mounting section.
Japanese Patent Laid-Open No. 7-262867 proposes a vehicle equipment control device endowed with a function for automatically discriminating between the types of control operations to be effected by different switches when the switches are mounted to arbitrary mounting sections. In this proposed vehicle equipment control device, there is provided for each switch a recognition signal generating means for outputting switch signals, which differ from switch to switch, when the switches are turned on. Further, a switch discrimination circuit which outputs an output signal for driving a predetermined load upon receiving a switch signal from the recognition signal generating means is provided in a control circuit unit, and the switches are replaced in a cassette-like manner, whereby a switch signal from the recognition signal generating means of the newly attached switch is read by the switch discrimination circuit. The recognition signal generating means have different internal wirings for different types of switch, and different switch signals are output when the switch contacts are turned on. These switch signals serve as recognition signals for indicating the uses of the switches. Further, the switch discrimination circuit has input terminals and logic circuits corresponding to the output terminals of the switches, and outputs driving signals to the loads corresponding to the functions of the switches by processing the switch signals from the switches by the logic circuits.
Thus, in this vehicle equipment control device, constructed as described above, there is no need to change the circuit configuration of the control circuit unit according to the grade, type, etc. of the vehicle, and it is possible to execute operations corresponding to the functions of the switches solely by exchanging a plurality of switches adapted to output different switch signals.
However, in the conventional device as described above, different switch signals are output from the recognition signal generating means by changing the internal wiring of the switches, and it is necessary to provide switches in a number corresponding to the functions of the switches with different internal wirings, so that not only is it impossible to use general-purpose switches, but the switch mounting position with respect to the printed circuit board must be changed each time the switch is mounted, resulting in an increase in production cost. Further, there are limitations as to the combination of the internal wirings on the switch side, and there are naturally limitaions as to the combination of logic circuits on the switch discrimination circuit side, so that it is difficult to cope with an increase in control functions.